This Applied Mitigation Bulletin is a companion document to the PSIRT
Security Advisory Multiple Vulnerabilities in Cisco Unified Customer Voice Portal Software and provides
identification and mitigation techniques that administrators can deploy on
Cisco network devices.

This document provides identification and mitigation techniques that
administrators can deploy on Cisco network devices.

Vulnerability Characteristics

There are multiple vulnerabilities in Cisco Unified Customer Voice Portal Software. The following subsections summarize these vulnerabilities:

Cisco Customer Voice Portal Malformed SIP INVITE Packet Vulnerability: This vulnerability can be
exploited remotely without authentication and
without end-user interaction. Successful exploitation of this
vulnerability could result in a denial of service (DoS) condition.

The attack vectors for exploitation are through IPv4 and
IPv6 packets using the following ports:

SIP using
TCP port 5060

SIP using
TCP port 5061

SIP using
UDP port 5060

SIP using
UDP port 5061

An
attacker could exploit these vulnerabilities using spoofed packets.

This vulnerability has been assigned Common Vulnerabilities and
Exposures (CVE) identifier CVE-2013-1220.

Cisco Unified Customer Voice Portal Insecure TomCat Web Applications Vulnerability: This vulnerability can be
exploited remotely without authentication and without end-user interaction. Successful exploitation of this
vulnerability could allow an attacker to escalate privileges and gain administrator access.

The attack vectors for exploitation are through IPv4 and
IPv6 packets using the following ports:

HTTP using
TCP port 80

HTTPS using
TCP port 443

This vulnerability has been assigned Common Vulnerabilities and
Exposures (CVE) identifier CVE-2013-1221.

Cisco Customer Voice Portal Insecure TomCat Configurations Vulnerability: This vulnerability can be
exploited remotely without authentication and
without end-user interaction. Successful exploitation of this
vulnerability could allow arbitrary code execution.

The attack vectors for exploitation are through IPv4 and
IPv6 packets using the following ports:

HTTP using
TCP port 80

HTTPS using
TCP port 443

This vulnerability has been assigned Common Vulnerabilities and
Exposures (CVE) identifier CVE-2013-1222.

Cisco Customer Voice Portal Arbitrary File Access Vulnerability: This vulnerability can be
exploited remotely without authentication and
without end-user interaction. Successful exploitation of this
vulnerability could allow information
disclosure, which enables an attacker to learn information about the affected
device.

The attack vectors for exploitation are through IPv4 and
IPv6 packets using the following ports:

HTTP using
TCP port 80

HTTPS using
TCP port 443

This vulnerability has been assigned Common Vulnerabilities and
Exposures (CVE) identifier CVE-2013-1223.

Cisco Customer Voice Portal Path Traversal Vulnerability: This vulnerability can be
exploited remotely without authentication and
without end-user interaction. Successful exploitation of this
vulnerability could allow arbitrary code execution.

The attack vectors for exploitation are through IPv4 and
IPv6 packets using the following ports:

HTTP using
TCP port 80

HTTPS using
TCP port 443

This vulnerability has been assigned Common Vulnerabilities and
Exposures (CVE) identifier CVE-2013-1224.

Cisco Customer Voice Portal XML Entity Expansion Vulnerability: This vulnerability can be
exploited remotely without authentication and
without end-user interaction. Successful exploitation of this
vulnerability could allow information
disclosure, which enables an attacker to learn information about the affected
device.

The attack vectors for exploitation are through IPv4 and
IPv6 packets using the following ports:

HTTP using
TCP port 80

HTTPS using
TCP port 443

This vulnerability has been assigned Common Vulnerabilities and
Exposures (CVE) identifier CVE-2013-1225.

Mitigation Technique Overview

Cisco devices provide several countermeasures for these vulnerabilities.
Administrators are advised to consider these protection methods to be general
security best practices for infrastructure devices and the traffic that
transits the network. This section of the document provides an overview of
these techniques.

Cisco IOS Software can provide effective means of exploit prevention using
the following methods:

Transit access control lists (tACLs)

Unicast Reverse Path Forwarding (uRPF)

IP source guard (IPSG)

These protection
mechanisms filter and drop, as well as verify the source IP address of, packets
that are attempting to exploit these vulnerabilities.

The proper deployment and
configuration of uRPF provides an effective means of protection against attacks
that use packets with spoofed source IP addresses. uRPF should be deployed as
close to all traffic sources as possible.

The proper deployment and
configuration of IPSG provides an effective means of protection against
spoofing attacks at the access layer.

Effective means of exploit prevention can also be provided by the Cisco ASA
5500 Series Adaptive Security Appliance, Cisco Catalyst 6500 Series ASA
Services Module (ASASM), and the Firewall Services Module (FWSM) for Cisco
Catalyst 6500 Series Switches and Cisco 7600 Series Routers using the
following:

Transit access control lists (tACLs)

Unicast Reverse Path Forwarding (uRPF)

These protection
mechanisms filter and drop, as well as verify the source IP address of, packets
that are attempting to exploit these vulnerabilities.

The Cisco Security Manager
can also provide visibility through incidents, queries, and event
reporting.

Risk Management

Organizations are advised to follow their standard risk evaluation and
mitigation processes to determine the potential impact of these vulnerabilities.
Triage refers to sorting projects and prioritizing efforts that are most likely
to be successful. Cisco has provided documents that can help organizations
develop a risk-based triage capability for their information security teams. Risk
Triage for Security Vulnerability Announcements and Risk
Triage and Prototyping can help organizations develop repeatable security
evaluation and response processes.

Caution:The effectiveness of any mitigation technique depends on specific customer situations such as product mix, network topology, traffic behavior, and organizational mission. As with any configuration change, evaluate the impact of this configuration prior to applying the change.

Specific information about mitigation and identification is available for these devices:

Mitigation: Transit Access Control Lists

To protect the network from traffic that enters the network at ingress
access points, which may include Internet connection points, partner and
supplier connection points, or VPN connection points, administrators are
advised to deploy transit access control lists (tACLs) to perform policy
enforcement. Administrators can construct a tACL by explicitly permitting only
authorized traffic to enter the network at ingress access points or permitting
authorized traffic to transit the network in accordance with existing security
policies and configurations. A tACL workaround cannot provide complete
protection against these vulnerabilities when the attack originates from a
trusted source address.

The tACL policy denies unauthorized SIP IPv4 and IPv6 packets on TCP and UDP ports 5060 and 5061. The policy also denies HTTP and HTTPS packets on TCP ports 80 and 443, respectively, when these packets are sent to affected devices. In the following example,
192.168.60.0/24 and 2001:DB8:1:60::/64 represent the IP address space that is
used by the affected devices, and the hosts at 192.168.100.1 and
2001:DB8::100:1 are considered trusted sources that require access to the
affected devices. Care should be taken to allow required traffic for routing
and administrative access prior to denying all unauthorized traffic.

Note that filtering with an interface access list will elicit the
transmission of ICMP unreachable messages back to the source of the filtered
traffic. Generating these messages could have the undesired effect of
increasing CPU utilization on the device. In Cisco IOS Software, ICMP
unreachable generation is limited to one packet every 500 milliseconds by
default. ICMP unreachable message generation can be disabled using the
interface configuration commands no ip unreachables and no
ipv6 unreachables. ICMP unreachable
rate limiting can be changed from the default using the global configuration
commands ip icmp rate-limit unreachableinterval-in-ms and ipv6 icmp error-intervalinterval-in-ms.

Identification: Transit Access Control Lists

After the administrator applies the tACL to an interface, show ip
access-lists and show ipv6 access-list commands will
identify the number of SIP IPv4 and IPv6 packets on TCP and UDP ports 5060 and 5061 and HTTP and HTTPS IPv4 and IPv6 packets on TCP ports 80 and 443 that have
been filtered. Administrators are advised to investigate filtered packets to
determine whether they are attempts to exploit these vulnerabilities. Example
output for show ip access-lists 150 and show ipv6
access-list IPv6-Transit-ACL-Policy follows:

Administrators can use Embedded Event Manager to provide instrumentation
when specific conditions are met, such as ACE counter hits. The Cisco Security
Intelligence Operations white paper Embedded
Event Manager in a Security Context provides additional details about how
to use this feature.

Identification: Access List Logging

The log and log-input access control list
(ACL) option will cause packets that match specific ACEs to be logged. The
log-input option enables logging of the ingress interface in
addition to the packet source and destination IP addresses and ports.

Caution: Access control list logging can be very CPU
intensive and must be used with extreme caution. Factors that drive the CPU
impact of ACL logging are log generation, log transmission, and process
switching to forward packets that match log-enabled ACEs.

The CPU impact from ACL logging can be addressed in hardware on the Cisco
Catalyst 6500 Series Switches and Cisco 7600 Series Routers with Supervisor
Engine 720 or Supervisor Engine 32 using optimized ACL logging.

Mitigation: Spoofing Protection

Unicast Reverse Path Forwarding

The vulnerabilities that are described in this document can be exploited by
spoofed IP packets. Administrators can deploy and configure Unicast Reverse
Path Forwarding (uRPF) as a protection mechanism against spoofing.

uRPF is configured at the interface level and can detect and drop packets
that lack a verifiable source IP address. Administrators should not rely on
uRPF to provide complete spoofing protection because spoofed packets may enter
the network through a uRPF-enabled interface if an appropriate return route to
the source IP address exists. Administrators are advised to take care to ensure
that the appropriate uRPF mode (loose or strict) is configured during the
deployment of this feature because it can drop legitimate traffic that is
transiting the network. In an enterprise environment, uRPF may be enabled at
the Internet edge and the internal access layer on the user-supporting Layer 3
interfaces.

IP source guard (IPSG) is a security feature that restricts IP traffic on
nonrouted, Layer 2 interfaces by filtering packets based on the DHCP snooping
binding database and manually configured IP source bindings. Administrators can
use IPSG to prevent attacks from an attacker who attempts to spoof packets by
forging the source IP address and/or the MAC address. When properly deployed
and configured, IPSG coupled with strict mode uRPF provides the most effective
means of spoofing protection for the vulnerabilities that are described in this
document.

With uRPF properly deployed and configured throughout the network
infrastructure, administrators can use the show cef interfacetype slot/portinternal, show ip
interface, show cef drop, show ip cef
switching statistics feature, and show ip traffic
commands to identify the number of packets that uRPF has dropped.

Note: The showcommand|
beginregex and showcommand| includeregex command modifiers are used in the
following examples to minimize the amount of output that administrators will
need to parse to view the desired information. Additional information about
command modifiers is in the show
command sections of the Cisco IOS Configuration Fundamentals Command
Reference.

In the preceding show cef interfacetype slot/portinternal, show cef drop, show ip
interfacetype slot/portand show ipv6 interfacetype slot/port, show ip cef switching statistics
feature and show ipv6 cef
switching statistics feature, and
show ip traffic and
show ipv6 trafficexamples,
uRPF has dropped the
following packets received globally on all interfaces with uRPF configured
because of the inability to verify the source address of the IP packets within
the forwarding information base of Cisco Express Forwarding.

Administrators can configure Cisco IOS NetFlow on Cisco IOS routers and
switches to aid in the identification of IPv4 traffic flows that may be
attempts to exploit these vulnerabilities. Administrators are advised to
investigate flows to determine whether they are attempts to exploit these
vulnerabilities or whether they are legitimate traffic flows.

This traffic is sent to
addresses within the 192.168.60.0/24 address block, which is used by affected devices. The packets in these flows
may be spoofed and may indicate an attempt to exploit these vulnerabilities.
Administrators are advised to compare these flows to baseline utilization for
SIP traffic sent on UDP ports
5060 and 5061 and also investigate the flows to determine whether they are
sourced from untrusted hosts or networks.

As shown in the following example, to view only the SIP packets on TCP ports 5060 (hex value 13C4) and 5061 (hex value 13C5) and HTTP and HTTPS packets on TCP port 80 (hex value 0050) and TCP port 443 (hex value 01BB),
use the show ip cache flow | include
SrcIf|_PrHex_.*(13C4|13C5|0050|01BB)_ command to display
the related Cisco NetFlow records:

As shown in the following example, to view only the SIP packets on UDP ports 5060 (hex value 13C4) and 5061 (hex value 13C5),
use the show ip cache flow | include
SrcIf|_PrHex_.*(13C4|13C5)_ command to display
the related Cisco NetFlow records:

Administrators can configure Cisco IOS NetFlow on Cisco IOS routers and
switches to aid in the identification of IPv6 traffic flows that may be
attempts to exploit the vulnerabilities that are described in this document.
Administrators are advised to investigate flows to determine whether they are
attempts to exploit these vulnerabilities or whether they are legitimate
traffic flows.

The following output is from a Cisco IOS device running Cisco IOS Software
12.4 mainline train. The command syntax will vary for different Cisco IOS
Software trains.

The SIP
packets on UDP ports 5060 and 5061 are sent to addresses within
the 2001:DB8:1:60::/64 address block that is used by affected devices. The
packets in the UDP flows may be spoofed and could indicate an attempt to
exploit these vulnerabilities. Administrators are advised to compare these
flows to baseline utilization for SIP
traffic on UDP ports 5060 and 5061 and also investigate the flows to determine
whether they are sourced from untrusted hosts or networks.

As shown in the following example, to view only the SIP packets on TCP ports 5060 (hex value 13C4) and 5061 (hex value 13C5),
and HTTP and HTTPS packets on TCP ports 80 (hex value 0050) and 443 (hex value 01BB), use the show ipv6 flow cache | include
SrcIf|_PrHex_.*(13C4|13C5|0050|01BB)_ command to display
the related Cisco NetFlow records:

As shown in the following example, to view only the SIP packets on UDP ports 5060 (hex value 13C4) and 5061 (hex value 13C5),
use the show ipv6 flow cache | include
SrcIf|_PrHex_.*(13C4|13C5)_ command to display
the related Cisco NetFlow records:

Introduced in Cisco IOS Software Releases 12.2(31)SB2 and 12.4(9)T, Cisco
IOS Flexible NetFlow improves original Cisco NetFlow by adding the capability
to customize the traffic analysis parameters for the administrator's specific
requirements. Original Cisco NetFlow uses a fixed seven tuples of IP
information to identify a flow, whereas Cisco IOS Flexible NetFlow allows the
flow to be user defined. It facilitates the creation of more complex
configurations for traffic analysis and data export by using reusable
configuration components.

The following example output is from a Cisco IOS device that is running a
version of Cisco IOS Software in the 15.1T train. Although the
syntax will be almost identical for the 12.4T and 15.0 trains, it may vary
slightly depending on the actual Cisco IOS release being used. In the following
configuration, Cisco IOS Flexible NetFlow will collect information on interface
GigabitEthernet0/0 for incoming IPv4 flows based on source IPv4 address, as
defined by the match ipv4 source address key field statement.
Cisco IOS Flexible NetFlow will also include nonkey field information about
source and destination IPv4 addresses, protocol, ports (if present), ingress
and egress interfaces, and packets per flow.

To only view the
SIP packets
on TCP port
5060 and 5061, and HTTP and HTTPS packets on TCP ports 80 and 443 respectively, use the show flow monitor
FLOW-MONITOR-ipv4 cache format table | include IPV4 DST ADDR
|_(5060|5061|80|443)_.*_6_ command to display the related
NetFlow records.

To only view the SIP packets on UDP ports 5060 and 5061, use the show flow monitor
FLOW-MONITOR-ipv4 cache format table | include IPV4 DST ADDR
|_(5060|5061)_.*_17_ command to display the related
NetFlow records.

The following example output is from a Cisco IOS device that is running a
version of Cisco IOS Software in the 15.1T train. Although the
syntax will be almost identical for the 12.4T and 15.0 trains, it may vary
slightly depending on the actual Cisco IOS release being used. In the following
configuration, Cisco IOS Flexible NetFlow will collect information on interface
GigabitEthernet0/0 for incoming IPv6 flows based on the source IPv6 address, as
defined by the match ipv6 source address key field statement.
Cisco IOS Flexible NetFlow will also include nonkey field information about
source and destination IPv6 addresses, protocol, ports (if present), ingress
and egress interfaces, and packets per flow.

Mitigation: Transit Access Control Lists

To protect the network from traffic that enters the network at ingress
access points, which may include Internet connection points, partner and
supplier connection points, or VPN connection points, administrators are
advised to deploy tACLs to perform policy enforcement. Administrators can
construct a tACL by explicitly permitting only authorized traffic to enter the
network at ingress access points or permitting authorized traffic to transit
the network in accordance with existing security policies and configurations. A
tACL workaround cannot provide complete protection against these
vulnerabilities when the attack originates from a trusted source address.

The tACL policy denies unauthorized SIP IPv4 and IPv6 packets on TCP and UDP ports 5060 and 5061. The policy also denies HTTP and HTTPS packets on TCP ports 80 and 443, respectively, when these packets are sent to affected devices. In the following example,
192.168.60.0/24 and 2001:DB8:1:60::/64 represent the IP address space that is
used by the affected devices, and the hosts at 192.168.100.1 and
2001:DB8::100:1 are considered trusted sources that require access to the
affected devices. Care should be taken to allow required traffic for routing
and administrative access prior to denying all unauthorized traffic.

Identification: Transit Access Control Lists

After the tACL has been applied to an interface, administrators can use the
show access-list command to identify the number of SIP IPv4 and IPv6 packets on TCP and UDP ports 5060 and 5061 and HTTP and HTTPS IPv4 and IPv6 packets on TCP ports 80 and 443 that have been filtered. Administrators are
advised to investigate filtered packets to determine whether they are attempts
to exploit these vulnerabilities. Example output for show access-list
tACL-Policy and show access-list IPv6-tACL-Policy
follows:

In the preceding example, access list IPv6-tACL-Policy has dropped
the following packets received from an untrusted host or network:

47 SIP packets on TCP port
5060 for ACE line 7

33 SIP packets on TCP port
5061 for ACE line 8

216 SIP packets on UDP port
5060 for ACE line 9

137 SIP packets on UDP port 5061 for ACE line 10

7 HTTP packets on TCP port
80 for ACE line 11

8 HTTPS packets on TCP port
443 for ACE line 12

In addition, syslog message 106023 can provide valuable
information, which includes the source and destination IP address, the source
and destination port numbers, and the IP protocol for the denied packet.

In the following example, the show logging | grepregex command extracts syslog messages from the logging buffer on the
firewall. These messages provide additional information about denied packets
that could indicate potential attempts to exploit the vulnerabilities that are
described in this document. It is possible to use different regular expressions
with the grep keyword to search for specific data in the
logged messages.

In the following example, the show logging | grepregex command extracts syslog messages from the logging buffer on the
firewall. These messages provide additional information about denied packets
that could indicate potential attempts to exploit the vulnerabilities that are
described in this document. It is possible to use different regular expressions
with the grep keyword to search for specific data in the
logged messages.

Identification: Cisco Security Manager

Cisco Security Manager, Event Viewer

Beginning in software version 4.0, Cisco Security Manager can collect
syslogs from Cisco firewalls and provides the Event
Viewer, which can query for events that are related to the vulnerabilities that
are described in this document.

Using the following filters in the Firewall Denied Events
predefined view in the Event Viewer provides all captured Cisco firewall access
list deny syslog messages that could indicate potential
attempts to exploit the vulnerabilities that are described in this document.

Use the Destination event filter to filter network objects that contain
the IP address space that is used by the affected devices (for example,
IPv4 address range 192.168.60.0/24 and IPv6 address range
2001:DB8:1:60::/64)

Use the Destination Service event filter to filter objects that contain
TCP ports 5060, 5061, 80, and 443, and UDP ports 5060 and 5061

An Event Type ID filter can be used with the Firewall Denied
Events predefined view in the Event Viewer to filter the syslog IDs
shown in the following list to provide all captured Cisco firewall
deny syslog messages that could indicate potential attempts to
exploit the vulnerabilities that are described in this document:

ASA-4-106021 (uRPF spoofing)

ASA-4-106023 (ACL deny)

For more information about Cisco Security Manager Events, refer to the Filtering
and Querying Events section of the Cisco Security Manager User Guide.

Cisco Security Manager Report Manager

Cisco Security Manager will generate a Top Services report can be used with the
following configuration to generate a report of events that indicate potential
attempts to exploit the vulnerabilities that are described in this document:

Use the Destination IP network filter to filter network objects that
contain the IP address space that is used by the affected devices (for
example, IPv4 address range 192.168.60.0/24 and IPv6 address range
2001:DB8:1:60::/64)

Set an action of Deny on the Criteria settings page

Identification: Event Management System Partner Events

Cisco works with industry-leading Security Information and Event Management
(SIEM) companies through the Cisco
Developer Network. This partnership helps Cisco deliver validated and tested SIEM
systems that address business concerns such as long-term log archiving and
forensics, heterogeneous event correlation, and advanced compliance reporting.
Security Information and Event Management partner products can be leveraged to
collect events from Cisco devices and then query the collected events for deny syslog
messages from firewalls that could indicate potential attempts to exploit the
vulnerabilities that are described in this document. The queries can be made by Syslog ID as shown in the following list:

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The security vulnerability applies to the following combinations of products.

Primary Products:

Cisco

Cisco Unified Customer Voice Portal (CVP)

7.0 base, (1) | 8.5 (1) | 9.0 (1)

Associated Products:

N/A

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